The government should be prepared to legislate to ensure a gender balanced House of Commons if political parties won’t put in place measures to achieve parity themselves, a report by the Women’s and Equalities Committee has recommended.

Currently around 30 per cent of Britain’s 650 MPs are women, giving the UK a ranking of 48th globally for representation in the lower or single legislative chamber – down from 25th in 1999.

But in a report on women in the Commons beyond 2020 (when the next general election is due to be held), the Committee said that figure isn’t high enough, and has called on political parties and government alike to engineer an increase in female representation.

It advises that the parties adopt strategies for placing women in “winnable” seats and set out publicly their plans for putting more women in the Commons, chastising them for fielding mostly male candidates at the last election.

Government, the report adds, has committed to achieving women’s full and equal participation under the Sustainable Development Goals and therefore has a “role in setting and delivering national targets to achieve this”, including, it suggests, fining parties who fail to meet the 50 per cent target.

The report has been championed by Conservative MP and chairman of the Committee, Maria Miller, who said: “We are calling on political parties to publicly set out the measures they plan to take to increase the proportion and number of women parliamentary candidates in 2020. We must ensure that previous positive trends do not stagnate or reverse. There is no room for complacency.”

She added: “In their evidence to our inquiry, the leaders of political parties agreed that the Commons would benefit from gender equality, and a range of initiatives is in place to improve the situation. But we saw little to justify their confidence that these will be sufficient.

“We need concrete action plans. We need party leadership to provide clear and strong direction in working with local parties to deliver more women candidates. We need to see more women candidates in winnable seats.

“Above all, parties need to be transparent and accountable in their progress – or the lack of it.”

Miller has further admitted that she would like to see the strategy rolled out for other groups.

In response to a call on Twitter for quotas for “Black, asian, muslim, jewish, disabled, traveller [sic]” people, Miller agreed that the recommendations could be extended to other groups:

As you will have seen in the report we chose to focus on women but the findings could also be support other under represented groups https://t.co/WgHzyMBpgp

Miller’s enthusiasm for the social engineering project has caused alarm among Conservatives who favour merit-based criteria, threatening to cause a rift in the party.

A conservative councillor called her support for all-women shortlists “divisive”, while Ben Harris-Quinney, chairman of the Bow Group, the UK’s oldest conservative think tank, argued that the solution lay in bottom-up, not top-down strategies. He said that Miller’s preferred method of coercion would worsen, rather than improve the situation.